Porous Body Production via Talc Eutectic Reaction
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Solution Overview
Problem
Existing porous bodies used in exhaust-gas cleaning structures, such as honeycomb filters, have limitations in trapping particulate matter due to inadequate pore size distribution and flow rates, leading to suboptimal trapping capabilities.
Innovation Solution
A method for producing a porous body with a flow-rate-weighted mean diameter of 10 µm to 24 µm, achieved by mixing talc with an average particle size of 1 µm to 18 µm and an auxiliary raw material like zirconium oxide, followed by molding and firing at 1350°C to 1440°C, which suppresses the formation of excessively large or small pores and optimizes flow rates, thereby enhancing trapping capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pore size in porous bodies is increased to improve trapping capability, then the trapping capability is improved, but the flow rate distribution becomes uneven and excessively large pores are formed
Solution Approach 1:
The invention changes the particle size parameters of the base material within a specific range (D10: 3-7 μm, D50: 10-18 μm, D90: 15-25 μm) and controls the particle size distribution to achieve a flow-rate-weighted mean diameter of 10-24 μm. This parameter optimization resolves the contradiction by preventing excessively large pores while maintaining sufficient trapping capability.
Solution Approach 2:
The invention uses a composite mixture of base material particles with different size distributions (D10, D50, D90 values) to create a porous body with optimized pore structure. The combination of fine and coarse particles in specific proportions fills voids and prevents excessive pore enlargement, resolving the contradiction between trapping capability and pore size distribution.
2Reliability
If the pore size is decreased to improve trapping capability, then the trapping capability is improved, but the flow rate becomes excessively low and small pores are formed
Solution Approach 1:
The invention optimizes the particle size parameters within specific ranges (D10: 3-7 μm, D50: 10-18 μm, D90: 15-25 μm) to achieve a flow-rate-weighted mean diameter of 10-24 μm. This prevents excessively small pores while maintaining high trapping capability, resolving the contradiction between trapping performance and flow rate.
Solution Approach 2:
The invention creates local variations in pore size by using a distribution of particle sizes, where smaller particles fill gaps between larger particles. This local quality variation ensures that no single region has excessively small pores that would impede flow, while still maintaining overall high trapping capability.
3Productivity
If the flow rate is increased to improve throughput, then the throughput is improved, but the trapping capability decreases due to excessive flow rate
Solution Approach 1:
The invention introduces the flow-rate-weighted mean diameter parameter (Ru = 10-24 μm) that accounts for both pore size and flow rate. By optimizing this composite parameter through controlled particle size distribution, the invention achieves a balance where throughput is improved without sacrificing trapping capability, as the flow rate is distributed evenly across pores of appropriate sizes.
4Reliability
If the flow rate is decreased to improve trapping capability, then the trapping capability is improved, but the throughput decreases due to insufficient flow rate
Solution Approach 1:
The invention optimizes the flow-rate-weighted mean diameter to 10-24 μm, which prevents excessively low flow rates by ensuring adequate pore sizes. This parameter optimization allows the porous body to maintain high trapping capability while preserving sufficient throughput, resolving the contradiction between trapping performance and productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The produced porous body achieves a significantly higher trapping capability, with a flow-rate-weighted mean diameter of 10 µm to 24 µm and a difference of 2 µm or less, effectively capturing particulate matter and meeting stringent emission standards.
Implementation Method 1
auxiliary raw material containing a material that undergoes a eutectic reaction with talc
Implementation Method 2
a porous body having a flow-rate-weighted mean diameter Ru of 10 μm or more and 24 μm or less
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
A method for producing a porous body, comprising: a raw-material mixing step of mixing talc having an average particle size of 1 µm or more and 18 µm or less, alumina, an auxiliary raw material containing a material that undergoes a eutectic reaction with talc and being prepared in an amount so as to satisfy a weight ratio of 0.5% or more and 1.5% or less by weight relative to the talc, and a pore-forming agent, to provide green body; and a molding and firing step of molding the green body to provide a compact and firing this compact at a firing temperature of 1350°C to 1440°C.